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#ifdef __APPLE__
#include <ES2/gl.h>
#else
#include <GLES2/gl2.h>
#endif
#define STB_IMAGE_IMPLEMENTATION
#include <stb_image.h>
#if defined __ANDROID__ && defined DEBUG
#include <android/log.h>
#endif
static struct {
void (*file_reader)(const char *, char **, size_t *);
GLfloat matrix[4][4];
GLfloat angle;
GLsizei num_triangles, num_textures;
GLuint program, buffers[1], textures[];
} model = {
.angle = 0.0f,
.num_textures = 0
};
static const GLfloat pi = 3.1415926535897932384626433832795f;
void pv_parse(GLsizei *num_triangles, size_t *tex_name_len, const char *model, void *file_reader);
void pv_convert(float *data, char *texture);
static GLuint compile(GLenum type, const char *shader)
{
GLchar *data;
size_t len;
model.file_reader(shader, &data, &len);
GLuint id = glCreateShader(type);
glShaderSource(id, 1, &(const GLchar *){data}, NULL);
glCompileShader(id);
GLint compiled;
glGetShaderiv(id, GL_COMPILE_STATUS, &compiled);
if (!compiled) {
#ifdef DEBUG
GLint len = 0;
glGetShaderiv(id, GL_INFO_LOG_LENGTH, &len);
if (len > 1) {
char log[len + 1];
glGetShaderInfoLog(id, len, NULL, log);
#ifdef __ANDROID__
__android_log_print(ANDROID_LOG_ERROR, "libproductviewer", "%s", log);
#else
printf("%s\n", log);
#endif
}
#endif
glDeleteShader(id);
return 0;
}
return id;
}
void pv_texturize(const char *texture)
{
GLsizei w, h;
int comp;
unsigned char *image = stbi_load(texture, &w, &h, &comp, STBI_default);
GLint format = GL_RGBA;
if (comp == 3)
format = GL_RGB;
glTexImage2D(GL_TEXTURE_2D, 0, format, w, h, 0, format, GL_UNSIGNED_BYTE, image);
stbi_image_free(image);
}
void pv_init(const char *obj, void (*file_reader)(const char *, char **, size_t *),
const char *color, unsigned int width, unsigned int height)
{
size_t tex_name_len;
model.file_reader = file_reader;
pv_parse(&model.num_triangles, &tex_name_len, obj, file_reader);
GLfloat data[sizeof(GLfloat) * model.num_triangles * 5];
char texture[tex_name_len + 1];
pv_convert(data, texture);
GLfloat rgba[4] = { [3] = 1.0f };
for (size_t i = 0; i < strlen(color) / 2; i++) {
GLuint value;
sscanf((char[]){ color[i * 2], color[i * 2 + 1], '\0' }, "%x", &value);
rgba[i] = (GLfloat)value / 255.0f;
}
glClearColor(rgba[0], rgba[1], rgba[2], rgba[3]);
glViewport(0, 0, width, height);
glEnable(GL_CULL_FACE);
model.program = glCreateProgram();
GLuint vert_id = compile(GL_VERTEX_SHADER, "product.vert");
glAttachShader(model.program, vert_id);
glDeleteShader(vert_id);
GLuint frag_id = compile(GL_FRAGMENT_SHADER, "product.frag");
glAttachShader(model.program, frag_id);
glDeleteShader(frag_id);
glLinkProgram(model.program);
glUseProgram(model.program);
static const GLsizei stride = sizeof(GLfloat) * 5;
GLuint data_id;
glGenBuffers(1, &data_id);
glBindBuffer(GL_ARRAY_BUFFER, data_id);
model.buffers[0] = data_id;
glBufferData(GL_ARRAY_BUFFER, stride * model.num_triangles * 3, data, GL_STATIC_DRAW);
GLint position = glGetAttribLocation(model.program, "a_position");
glVertexAttribPointer(position, 3, GL_FLOAT, GL_FALSE, stride, 0);
glEnableVertexAttribArray(position);
GLint texcoord = glGetAttribLocation(model.program, "a_texcoord");
glVertexAttribPointer(texcoord, 2, GL_FLOAT, GL_FALSE, stride, (const void *)(sizeof(GLfloat) * 3));
glEnableVertexAttribArray(texcoord);
glActiveTexture(GL_TEXTURE0);
GLuint tex_id;
glGenTextures(1, &tex_id);
glBindTexture(GL_TEXTURE_2D, tex_id);
model.textures[model.num_textures++] = tex_id;
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glUniform1i(glGetUniformLocation(model.program, "s_texture"), 0);
pv_texturize(texture);
}
static void identity(GLfloat matrix[][4])
{
memset(matrix, 0x0, sizeof(GLfloat[4][4]));
for (int i = 0; i < 4; i++)
matrix[i][i] = 1.0f;
}
static void multiply(GLfloat matrix[][4], GLfloat a[][4], GLfloat b[][4])
{
GLfloat tmp[4][4];
for (int i = 0; i < 4; i++) {
tmp[i][0]
= a[i][0] * b[0][0]
+ a[i][1] * b[1][0]
+ a[i][2] * b[2][0]
+ a[i][3] * b[3][0];
tmp[i][1]
= a[i][0] * b[0][1]
+ a[i][1] * b[1][1]
+ a[i][2] * b[2][1]
+ a[i][3] * b[3][1];
tmp[i][2]
= a[i][0] * b[0][2]
+ a[i][1] * b[1][2]
+ a[i][2] * b[2][2]
+ a[i][3] * b[3][2];
tmp[i][3]
= a[i][0] * b[0][3]
+ a[i][1] * b[1][3]
+ a[i][2] * b[2][3]
+ a[i][3] * b[3][3];
}
memcpy(matrix, tmp, sizeof(GLfloat[4][4]));
}
static void translate(GLfloat matrix[][4], GLfloat x, GLfloat y, GLfloat z)
{
matrix[3][0] += (matrix[0][0] * x + matrix[1][0] * y + matrix[2][0] * z);
matrix[3][1] += (matrix[0][1] * x + matrix[1][1] * y + matrix[2][1] * z);
matrix[3][2] += (matrix[0][2] * x + matrix[1][2] * y + matrix[2][2] * z);
matrix[3][3] += (matrix[0][3] * x + matrix[1][3] * y + matrix[2][3] * z);
}
static void rotate(GLfloat matrix[][4], GLfloat angle, GLfloat x, GLfloat y, GLfloat z)
{
angle *= pi / 180.0f;
GLfloat sin_angle = sinf(angle);
GLfloat cos_angle = cosf(angle);
GLfloat mag = sqrtf(x * x + y * y + z * z);
if (mag > 0.0f) {
x /= mag;
y /= mag;
z /= mag;
GLfloat one_minus_cos = 1.0f - cos_angle;
multiply(matrix, (GLfloat[][4]){
(one_minus_cos * x * x) + cos_angle,
(one_minus_cos * x * y) - z * sin_angle,
(one_minus_cos * z * x) + y * sin_angle,
0.0f,
(one_minus_cos * x * y) + z * sin_angle,
(one_minus_cos * y * y) + cos_angle,
(one_minus_cos * y * z) - x * sin_angle,
0.0f,
(one_minus_cos * z * x) - y * sin_angle,
(one_minus_cos * y * z) + x * sin_angle,
(one_minus_cos * z * z) + cos_angle,
0.0f,
0.0f,
0.0f,
0.0f,
1.0f
},
matrix);
}
}
void pv_draw(unsigned int width, unsigned int height)
{
GLfloat perspective[4][4];
identity(perspective);
GLfloat near_z = 1.0f;
GLfloat far_z = 20.0f;
GLfloat delta_y = tanf(pi / 6.0f) * 2;
GLfloat delta_z = far_z - near_z;
multiply(perspective, (GLfloat[][4]){
2.0f * near_z / delta_y / (GLfloat)width * (GLfloat)height, 0.0f, 0.0f, 0.0f,
0.0f, 2.0f * near_z / delta_y, 0.0f, 0.0f,
0.0f, 0.0f, -(near_z + far_z) / delta_z, -1.0f,
0.0f, 0.0f, -2.0f * near_z * far_z / delta_z, 0.0f
},
perspective);
GLfloat model_view[4][4];
identity(model_view);
translate(model_view, 0.0, 0.0, -2.7);
rotate(model_view, -15.0, 1.0, 0.0, 0.0);
rotate(model_view, model.angle, 0.0, 1.0, 0.0);
multiply(model.matrix, model_view, perspective);
glUniformMatrix4fv(glGetUniformLocation(model.program, "u_matrix"), 1, GL_FALSE, &model.matrix[0][0]);
glClear(GL_COLOR_BUFFER_BIT);
glDrawArrays(GL_TRIANGLES, 0, model.num_triangles * 3);
}
void pv_rotate(GLfloat angle)
{
model.angle += angle;
if (model.angle >= 360.0f)
model.angle -= 360.0f;
}
void pv_quit()
{
glDeleteTextures(model.num_textures, model.textures);
glDeleteBuffers(1, model.buffers);
glDeleteProgram(model.program);
}
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